/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.remoting.rmi;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.util.Properties;
import javax.naming.NamingException;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.jndi.JndiTemplate;
import org.springframework.lang.Nullable;
import org.springframework.util.ReflectionUtils;

/**
 * Service exporter which binds RMI services to JNDI.
 * Typically used for RMI-IIOP (CORBA).
 *
 * <p>Exports services via the {@link javax.rmi.PortableRemoteObject} class.
 * You need to run "rmic" with the "-iiop" option to generate corresponding
 * stubs and skeletons for each exported service.
 *
 * <p>Also supports exposing any non-RMI service via RMI invokers, to be accessed
 * via {@link JndiRmiClientInterceptor} / {@link JndiRmiProxyFactoryBean}'s
 * automatic detection of such invokers.
 *
 * <p>With an RMI invoker, RMI communication works on the {@link RmiInvocationHandler}
 * level, needing only one stub for any service. Service interfaces do not have to
 * extend {@code java.rmi.Remote} or throw {@code java.rmi.RemoteException}
 * on all methods, but in and out parameters have to be serializable.
 *
 * <p>The JNDI environment can be specified as "jndiEnvironment" bean property,
 * or be configured in a {@code jndi.properties} file or as system properties.
 * For example:
 *
 * <pre class="code">&lt;property name="jndiEnvironment"&gt;
 * 	 &lt;props>
 * 		 &lt;prop key="java.naming.factory.initial"&gt;com.sun.jndi.cosnaming.CNCtxFactory&lt;/prop&gt;
 * 		 &lt;prop key="java.naming.provider.url"&gt;iiop://localhost:1050&lt;/prop&gt;
 * 	 &lt;/props&gt;
 * &lt;/property&gt;</pre>
 *
 * @author Juergen Hoeller
 * @see #setService
 * @see #setJndiTemplate
 * @see #setJndiEnvironment
 * @see #setJndiName
 * @see JndiRmiClientInterceptor
 * @see JndiRmiProxyFactoryBean
 * @see javax.rmi.PortableRemoteObject#exportObject
 * @since 1.1
 */
public class JndiRmiServiceExporter extends RmiBasedExporter implements InitializingBean, DisposableBean {

    @Nullable
    private static Method exportObject;

    @Nullable
    private static Method unexportObject;

    static {
        try {
            Class<?> portableRemoteObject =
                    JndiRmiServiceExporter.class.getClassLoader().loadClass("javax.rmi.PortableRemoteObject");
            exportObject = portableRemoteObject.getMethod("exportObject", Remote.class);
            unexportObject = portableRemoteObject.getMethod("unexportObject", Remote.class);
        } catch (Throwable ex) {
            // java.corba module not available on JDK 9+
            exportObject = null;
            unexportObject = null;
        }
    }


    private JndiTemplate jndiTemplate = new JndiTemplate();

    private String jndiName;

    private Remote exportedObject;


    /**
     * Set the JNDI template to use for JNDI lookups.
     * You can also specify JNDI environment settings via "jndiEnvironment".
     *
     * @see #setJndiEnvironment
     */
    public void setJndiTemplate(JndiTemplate jndiTemplate) {
        this.jndiTemplate = (jndiTemplate != null ? jndiTemplate : new JndiTemplate());
    }

    /**
     * Set the JNDI environment to use for JNDI lookups.
     * Creates a JndiTemplate with the given environment settings.
     *
     * @see #setJndiTemplate
     */
    public void setJndiEnvironment(Properties jndiEnvironment) {
        this.jndiTemplate = new JndiTemplate(jndiEnvironment);
    }

    /**
     * Set the JNDI name of the exported RMI service.
     */
    public void setJndiName(String jndiName) {
        this.jndiName = jndiName;
    }


    @Override
    public void afterPropertiesSet() throws NamingException, RemoteException {
        prepare();
    }

    /**
     * Initialize this service exporter, binding the specified service to JNDI.
     *
     * @throws NamingException if service binding failed
     * @throws RemoteException if service export failed
     */
    public void prepare() throws NamingException, RemoteException {
        if (this.jndiName == null) {
            throw new IllegalArgumentException("Property 'jndiName' is required");
        }

        // Initialize and cache exported object.
        this.exportedObject = getObjectToExport();
        invokePortableRemoteObject(exportObject);

        rebind();
    }

    /**
     * Rebind the specified service to JNDI, for recovering in case
     * of the target registry having been restarted.
     *
     * @throws NamingException if service binding failed
     */
    public void rebind() throws NamingException {
        if (logger.isDebugEnabled()) {
            logger.debug("Binding RMI service to JNDI location [" + this.jndiName + "]");
        }
        this.jndiTemplate.rebind(this.jndiName, this.exportedObject);
    }

    /**
     * Unbind the RMI service from JNDI on bean factory shutdown.
     */
    @Override
    public void destroy() throws NamingException, RemoteException {
        if (logger.isDebugEnabled()) {
            logger.debug("Unbinding RMI service from JNDI location [" + this.jndiName + "]");
        }
        this.jndiTemplate.unbind(this.jndiName);
        invokePortableRemoteObject(unexportObject);
    }


    private void invokePortableRemoteObject(@Nullable Method method) throws RemoteException {
        if (method != null) {
            try {
                method.invoke(null, this.exportedObject);
            } catch (InvocationTargetException ex) {
                Throwable targetEx = ex.getTargetException();
                if (targetEx instanceof RemoteException) {
                    throw (RemoteException) targetEx;
                }
                ReflectionUtils.rethrowRuntimeException(targetEx);
            } catch (Throwable ex) {
                throw new IllegalStateException("PortableRemoteObject invocation failed", ex);
            }
        }
    }

}
